Add UMA stats to record when DLLs are successfully blocked in the Browser.

chrome_elf/blacklist/blacklist.cc

Index: chrome_elf/blacklist/blacklist.cc
diff --git a/chrome_elf/blacklist/blacklist.cc b/chrome_elf/blacklist/blacklist.cc
index 958d7103b798ba5488b8d9857f7be6a06c20cecb..566a675c1172229de4b74236bfc45e406d1dfdd8 100644
--- a/chrome_elf/blacklist/blacklist.cc
+++ b/chrome_elf/blacklist/blacklist.cc
@@ -28,6 +28,9 @@ const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount] = {
   NULL,
 };
 
+bool g_blocked_dlls[kTroublesomeDllsMaxCount] = {false};

[robertshield, 2014/02/25 03:21:40]

"= {}" works for bool arrays too.

[csharp, 2014/02/25 14:45:00]

Done.

+int g_num_blocked_dlls = 0;
+
 const wchar_t kRegistryBeaconPath[] = L"SOFTWARE\\Google\\Chrome\\BLBeacon";
 const wchar_t kBeaconVersion[] = L"version";
 const wchar_t kBeaconState[] = L"state";
@@ -298,6 +301,7 @@ bool AddDllToBlacklist(const wchar_t* dll_name) {
   wcscpy(str_buffer, dll_name);
 
   g_troublesome_dlls[blacklist_size] = str_buffer;
+  g_blocked_dlls[blacklist_size] = false;
   return true;
 }
 
@@ -310,12 +314,48 @@ bool RemoveDllFromBlacklist(const wchar_t* dll_name) {
       delete[] g_troublesome_dlls[i];
       g_troublesome_dlls[i] = g_troublesome_dlls[blacklist_size - 1];
       g_troublesome_dlls[blacklist_size - 1] = NULL;
+
+      // Also update the stats recording if we have blocked this dll or not.
+      if (g_blocked_dlls[i])
+        --g_num_blocked_dlls;
+      g_blocked_dlls[i] = g_blocked_dlls[blacklist_size - 1];
       return true;
     }
   }
   return false;
 }
 
+// TODO(csharp): Maybe store these values in the registry so we can
+// still report them if Chrome crashes early.
+void SuccessfullyBlocked(const wchar_t** blocked_dlls, int* size) {
+  if (size == NULL)
+    return;
+
+  // If the array isn't valid or big enough, just report the size it needs to
+  // be and return.
+  if (blocked_dlls == NULL && *size < g_num_blocked_dlls) {
+    *size = g_num_blocked_dlls;

[robertshield, 2014/02/25 03:21:40]

The comment on this method states that |size| will always be filled, but the
implementation appears to only do so when the value in |size| starts off too
small?

[csharp, 2014/02/25 14:45:00]

Comment is correct, fixed code.

+    return;
+  }
+
+  int strings_to_fill = 0;
+  for (int i = 0;
+       strings_to_fill != g_num_blocked_dlls && g_troublesome_dlls[i];

[robertshield, 2014/02/25 03:21:40]

|strings_to_fill| indexes into |blocked_dlls| and so should be checked against
|size|, also prefer < to != for integer checks

[csharp, 2014/02/25 14:45:00]

Replaced != with <, also |size| >= |g_num_blocked_dlls| so we don't need that
check (if that condition is false we would have already exited)

+       ++i) {

[robertshield, 2014/02/25 03:21:40]

I know I said to break here earlier,  but if you can wrap the increment to the
previous line, that would be ok. Also, see what git cl format does.

[csharp, 2014/02/25 14:45:00]

git cl format seems to like merging line 342 and 343

+    if (g_blocked_dlls[i]) {
+      blocked_dlls[strings_to_fill] = g_troublesome_dlls[i];
+      ++strings_to_fill;
+    }
+  }
+}
+
+void BlockedDll(int blocked_index) {

[robertshield, 2014/02/25 03:21:40]

check |blocked_index| against kTroublesomeDllsMaxCount. Also, use a size_t as a
parameter rather than a signed int (should also change the type of
kTroublesomeDllsMaxCount in the process).

[csharp, 2014/02/25 14:45:00]

Done.

+  if (!g_blocked_dlls[blocked_index]) {
+    ++g_num_blocked_dlls;
+    g_blocked_dlls[blocked_index] = true;
+  }
+}
+
 bool Initialize(bool force) {
   // Check to see that we found the functions we need in ntdll.
   if (!InitializeInterceptImports())